Assignment problem:
Let us say you outlined the physical security threats to the United States, your state, and your hometown. Are you ready to cope with and survive the consequences of such critical physical security threats?
According to Presidential Policy Directive 21 (PPD-21), what are the federal government's roles and responsibilities towards federal, state, local, tribal, and territorial (SLTT) entities and public and private owners/operators of critical infrastructure?
Remember to support your statements with examples and references.